The Zen of STARs (and SlDs)

Is there any advantage to filing them ahead of time, or should you just let ATC come up with the plan? Jeff Klein, an ATP/CFII who instructs from Arlington, Texas, takes us through the ins and outs of getting in and out.

By Jeff Klein
, This article originally appeared in IFR MAGAZINE and is reproduced here by permission of Belvoir Publications. | July 22, 1996

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If you've looked at the instrument written booklet lately, you'll
notice that although there are some new questions here and there,
not much has changed. The written is heavy on regs, theory and
weather but light on the real meat-and-potatoes grit of IFR flying.
This is especially true of how the feds treat SIDs and STARs.

Consider, for example, the elaborate time en route problems involving
standard instrument departures. Instrument-pilots-to-be spend
hours sweating over these things, only to learn that (a) the multiple
guess answers are too close to be resolved by an E-6B and (b)
no one ever does these calculations in the real world anyway.
In fact, apart from the test writers in Oklahoma City, maybe no
one ever has done such calculations.

Even though it's misdirected, the emphasis on SIDs and STARs is
not misplaced. These procedures are a part of everyday IFR flying
and if you routinely pencil in "NO SIDs/NO STARs" on
your flight plan, you're denying yourself the occasional shortcut
or, at the least, missing an opportunity to learn how ATC works.
So, how do you use SIDs and STARs? Should you use them at all?
What are the pitfalls?

Where They Come From

SIDs (standard instrument departures) and STARs (standard terminal
arrival routes) appear in both Jeppesen and NOS publications.
Jeppesen bundles them together with the approaches. NOS groups
the arrivals at the front of the booklets while the SIDs are paired
with the approaches.

Personally I like the way the STARs appear, since it saves duplication.
But why didn't they do the SIDs the same way? I didn't check carefully,
but I saw the Regional Six departure printed on 10 different pages
in the same NOS booklet. Jeppesen does the same, of course, meaning
you might get to file one SID 10 times.

Even though we consider them instrument procedures for pilots
to use, SIDs and STARs aren't there primarily to make the pilot's
life easier. SIDs and STARs exist chiefly to make it easy on ATC.
The idea is this: It's a lot easier for a controller to say "cleared
to Kansas City via the San Jose Seven Departure, J12," than
it is "cleared to Kansas City via runway heading to the San
Jose VORDME 1.8, then right to heading 110, to cross the San Jose
47-degree radial at or below 5000 feet, intercept the Oakland
121degree radial to MOONY, J12..."

The point is, SIDs and STARs allow ATC to codify commonly used
clearances and procedures. Essentially, they buy frequency time
and, for that reason, SIDs and STARs make it easy on both controllers
and pilots. Also, SIDs and STARs give ATC a means to communicate
to the pilot what his or her routing is likely to be when departing
or arriving. By reviewing that ahead of time-or by filing the
procedure in the first place-the pilot can plan accordingly.

SIDs for Flibs

Light aircraft IFR pilots routinely encounter SIDs. They're used
almost everywhere, at towered fields served by some kind of approach
control. Some are complex-such as the previously described San
Jose Seven- while others consist of nothing more than "runway
heading" to a specific altitude. Why such a simple clearance
requires a SID is beyond us. We don't make the rules, we just
try to avoid breaking too many of them.

As fully described in section 5-26 of the AIM, SIDs come in two
types: pilot nav and vector SIDs. In practice, some SIDs seem
to be a little of both. Pilot nav SIDs imply that the pilot is
equipped to navigate the SID and that he or she will do so without
any intervention from federal authorities. If the clearance reads
"via the San Jose Seven departure," the pilot is authorized
and expected to follow every little twist and niggle in the route,
unless ATC comes up with another plan.

Pilot nav SIDs are clearly labeled as such, in the title on both
NOS and Jeppesen plates. Not that you could get confused. Pilot
nav SIDs usually have a fat slug of type describing the various
courses and altitudes the pilot is supposed to fly. Vector SIDs,
on the other hand, usually give a heading and maybe a fix or two
before the word "thence, " which is ATC's rather biblical
way of saying expect vectors or resume own navigation.

SIDs are really pretty simple. So simple, in fact, that we wonder
why so many pilots duck them by adding "NO SIDs" to
the remarks. There are a few traps to worry about, however. One
obvious point is to make sure you have and follow the correct
and current SID. Many airports have several SIDs for the same
runway and pilots have been known to fly the wrong one. Watch
out for expired-plate syndrome, too. Altitudes, courses and frequencies
on SIDs change more often than you might think. Expired plates
just won't hack it.

Watch That Altitude!

Some SIDs are performance based, meaning that you're expected
to be able to maintain a minimum climb gradient in order to accept
the SID. The gradient may be necessary for terrain clearance or
to meet an ATC crossing restriction. If you fall short of the
gradient, you could become part of the local topography or, at
the very least, get spanked by ATC for messing up the departure
sequence. Either way, check the chart carefully and use the gradient-to-rate
table to convert the required climb to a feet-per-minute value.
If no special climb gradient is specified, the assumed climb gradient
is 200 feet per mile, or about 333 feet per minute at 100 knots.
The same assumed gradient, by the way, applies to ordinary unnamed
instrument departure procedures found at towered and non towered
airports.

Pilot nav SIDs always (well, almost) specify the initial altitude.
Vector SIDs sometimes do, too. But often that altitude comes with
the clearance. Some pilots have been thoroughly confused by a
clearance with an altitude other than that given in the SID. Which
altitude takes precedence, that on the SID or the one given in
the clearance? Frankly, we don't know. We've been told that local
custom applies to this one. When an altitude other than that on
the SID is given, most controllers are careful to emphasize it.
But you can't count on that. The best way to sort it out is to
ask the controller to clarify the clearance.

STARs

Standard terminal arrival routes are largely the province of heavy
jets or al least relatively fast traffic descending from the flight
levels. Some even say as much. Notes such as "applicable
to turbojets only" or "all aircraft operating 11,000
feet and above" tell the story. If you're a piston driver
operating at low altitude, you can forget flying those STARs.
Even if you're a high falutin' Mooney 252 pilot used to cruising
at FL240, you might be too slow to keep up with the jets populating
the SIDs. You'll either get turned off the route or, more likely,
descended and brought in under the jet traffic.

But that doesn't mean you should forget STARs entirely. These
procedures do offer important clues about the traffic flow into
major terminals, information that's useful for flight planning,
whether you're VFR or IFR. In some parts of the country, such
as Dallas-Fort Worth, where I operate, STARs are used commonly
for low altitude traffic. It really depends on the whim of the
of local ATC facility, since that's where the procedures originate.

Let's examine the Acton Two Arrival (AQN.AQN.2) for DF/W to see
how it can work. Let's assume we're flying a piston single on
a short 50-mile trip coming into the D/FW area from Waco. Let's
say we file 5000 feet, direct to our destination, Arlington, Texas.
In case you're wondering, there's no chance we'll get that routing.
IFR traffic into DF/W is routed over one of four "gatepost"
VORs that form a square around the metro area.

With that in mind, clearance delivery will come back with something
like this: "Cleared to the Arlington Airport, via Victor
17 Acton, the Acton Two arrival, maintain 5000 feet, departure
frequency 135.2..." Pilots not accustomed to flying low-altitude
STARs may be surprised by that clearance, since the STAR goes
to small muni field with no tower.

Step one is to make sure the STAR goes to your destination. If
it doesn't, you can't get there from here, period. Step two is
to forget about the picture and go to the text on the back of
the page. For this particular STAR (and many others around Dallas)
the map is a nightmare. The arrival description cuts through the
clag, though. It lists various categories of aircraft: Turbojets
landing at Dallas. ..that's not us. . .Non-turbojets landing at
Dallas...closer, but no cigar. Finally, under "All aircraft
landing at Arlington," we see these instructions: "From
over AQN VORTAC, R-079 to BRITY, expect vectors final approach
course."

Real Life

So, remembering that STARs are meant to simplify clearance delivery
procedures, all we really needed to know is that Victor 17 takes
us to Acton VOR and from there, we're going to track the R-079
outbound and get vectors. If you had used NO SIDs/STARs in your
flight plan, that's exactly what you would have gotten anyway.

Does the clearance actually pan out in real life? Nope, probably
not. Often, an amendment is tacked on by Center: "Cherokee
Three Four Charlie, join the arrival east of Acton." Then,
as soon as Regional approach gets hold of you, you get vectors
to the final approach course, never having gotten near the published
STAR route. Why? Local traffic, probably. Could be there was faster
traffic closing up behind and it just worked better not to use
the STAR.

So why do they bother specifying it? ATC procedural inertia, mainly.
The Letters of Agreement have been written and the controllers
generally follow them, even though they know the routing won't
stand. What they don't know (at least when you depart) is what
the traffic picture will be when you prepare to enter the STAR,
which is why they don't cobble up a new route to begin with.

Lost communications is another reason. Say you lost comm before
the shortcut. You could turn east on the R-079 at the VOR, stay
out of everybody's way and safely continue to Arlington. If you
lost radios after the shortcut, same story.

Planning It

Is it possible to figure out in advance if STARs are in use and
if so, is it worth doing? Yes, it is possible and it 's also worth
doing, to the extent that it always makes sense to know as much
as you can about ATC 's plans. I can't think of any circumstance
where it's better to be in the dark.

The easiest way to plan is to look at the index of the approach
plates in NOS booklets. Look up the airport you're going to and
see what applies. The key is to read the arrival description to
see if low-altitude traffic is included. As I said earlier, make
sure your destination airport is served by the arrival. If it
isn't, don't bother filing it. ATC will hand you the preferred
routing anyway.

Most STARs (and SIDs) have transitions that are best thought of
as branch routes feeding the main procedure. The Acton Two, for
example, has the Wink, Abilene and EDNAS transitions, flown, respectively,
from the two VORs and an intersection. These transitions join
the STAR, then lead right to the Acton VOR. If you're expected
to fly the transition, the clearance will say that: "Cleared
to...via the Wink transition, Acton Two arrival...etc."

If you want to file a transition, the filing code is given right
on the chart. Let's say you were filing for Arlington from El
Paso, with the Wink transition. The route would read: ELP V16
INK.AQN2 F54. The computer would probably accept the routing,
but whether ATC would stick to it is anybody's guess. DUAT, by
the way, is supposed to accept SIDs and STARs, but will do so
only if the procedures appear in its database.

One last point about both SIDs and STARs: They provide the approach
and departure frequencies you will need. It's funny to listen
to the tower at Houston Hobby, where every clearance gives the
Hobby Eight, and no departure frequency is given. After takeoff,
the tower ships pilots to departure and some have to ask for the
freq, forgetting that it appears right on the SID. (The same applies
to STARs) Just remember to look it up before you take off.

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